Device for destroying sound waves, more especially utilizable as a silencer for combustion and explosion engines



April 29, 1941.

R. P POMIES DEVICE FOR DESTROYING SOUND W 2,240,052 AVES, MORE ESPECIALLY UTILIZABLE AS A SILENCER FOR COMBUSTION Am) EXPLQSION ENGINES Filed June 28, 1938 2 Sheets-Sheet 1 1NVENTQR= ROBERT PNERRE- POP HES BY fiwammd 2,240,052 MORE ESPECIALLY UTILIZABLE AS A sILErwEa FOR COIBUSTION mm EXPLOSION ENGINES 2 Sheets-Sheet 2 April R. P. POMIES DEVICE FOR DBSTROYING SOUND WAVES,

Filed June 28, 1938 QIQVENTOR O ERT \E E MlES A 1' RNEYS Patented Apr. 29, 1941 UNITED STATES PATENT I OFFICE DEVICE ron nns'momo SOUND swavns,

MORE ESPECIALLY summon:- Fon. COMBUSTION AND EX- PLOSION ENGINES Robert Pierre Pomies, Paris, France Application June as, 193s, Serial No. 216,195 In France June 3:0, 1937 9 Claims.

, pletely destroy the sound waves, but he obtains at the same time a considerable increase in the power of the engine.

In fact, in the means proposed by the applicant, any braking of the gases is avoided and the sound wave is separated from the gas which carries it. v

In its general principle, the invention consists in arranging, in the path of the hot exhaust gases of an engine, at least one expansion chamher in which said gases are introduced or from which they are exhausted, through a port of reduced width but of suiiicient cross-section to prevent braking, said port being located adjacent an outlet of gases from the chamber or an inlet into the latter, in such a manner that the oppositely directed gaseous inletand outlet streams (the densities of which are different owing to the expansion and the cooling of the gases in the chamber) cause vortical zones opposite the port.

Said vortical zones are kept up by the flow in opposite directions, of the gaseous streams and the vortices have a high speed which is in principle greater than the speed of, propagation of. sound.

The vortical zone or zones thus created form a regular screen for the sound wave which is destroyed, and this is effected without braking the flow of the gases.

In this diagrammatical embodiment, the destruction of the sound wave is eiIected, on the one hand by the vortical movements, and on the other hand by the change of density of the gases in which the sound propagates.

To these two factors there may be added a third factor of destruction which enables an interference to be created by reflection oi the sound wave.

The invention covers the combination, with the previously indicated means, of a second chamber UTILIZABLE AS A:

from "the first chamber and as an inlet into the second, enable, by the reflection of the sound wave on to the opposite ends of said chambers, an interference to be created in the pipe, the second chamber exhausting the gases into the atmosphere through a narrow port which, as in the first chamber and under the action of the two gaseous streams circulating in opposite directions, ,enables a second vertical zone to. be formed.

In an industrial embodiment, the chambers which are in opposition, are mounted on the exhaust pipe and are placed in communication chamber or from the chamber,

through a flattened pipe, said chambers being separated, outside the pipe, by a suitably inclined wall.

' It is obviousl'yip'ossible'to connect a plurality of devices in series, in parallel or in series-parallel.

In another embodiment with multiple chambers, the inclined wall is replaced by a cone provided radially and on the outside with flattened channels opening into chambers which are in principle evenly distributed along radii.

It is possible to combine two previously indicated systems in which the cones are in opposition, the interference being produced in the space limited by the cones.

It is also possible to connect a plurality of de- Nices in series, in parallel or in series-parallel.

In another embodiment, the exhaust of each cylinder is effected through a. nozzle which opens into a chamber, as indicated in the basic feature,

the various chambers being connected together by a manifold made up of a plurality of elements. The inlet or the outlet of the gases into the is effected through the intermediary oi. convergent or divergent walls.

The invention further covers other particular points which will become apparent from the ensuing specification taken with reference to the accompanying drawings which are only given by way of example and in which:

Fig. 1 is an explanatory'diagrammatical view in section of a first embodiment of a silencer taken on the left along the broken line II A. B.

which is arranged in opposition relatively to the,

first; said chambers, which are connected to'-" C. II of Fig. 3 and on the right along the straight line IIH of said figure.

Fig. 3 is a transverse section of the right hand gether axially by a pipe serving as an exhaust or left hand element of Fig. 2, said section being vie sniiiiionhe 2 taken in principle along the line III-III of said figure.

Fig. 8' is a partial view .of Fig. 3, but on a larger scale, in order to facilitate the illustration of a vortical zone. 1

Fig. I is an elevation, with a section taken,

along the line IV-IV of Fig. andshowing another industrial embodiment.

Fig. 5 is a section taken along the line V-'V of the arrow 1''. The cross-section of the pipe I is amply calculated so as not to produce any braking of the stream issuing from the manifold. Said pipe i communicates, through an annular port I, with a chamber 4 into which a tube I opens co-axially with the annular port I.

The exhaust gases penetrating by means of the pipe 1 into the chamber 4 through the annular space I, are cooled in said chamber; a balance of pressure is instantly set up and the gases escape through the conduit I in the direction of the arrow 1".

The elementary apparatus could be limited to themain parts which were previously indicated.

range suitably the chambers 4, s and the pipe 5. In fact, the sound wave is reflected on to the opposite walls I' and I of the chambers 4 and By suitably arrangingthe annular port I and the inlet I relatively to each other, a very rapid toricvortical mne'l isset upbetweenthestream which enters the chamber 4 (hot gases of. low density) and the stream issuing from said chamber 4 (cooled gases of greater density). This vertical movement I is produced hy the friction of the two gaseous streams of difl'erent densities circulating in opposite directions.

The annular port I is of relatively small width but of sufiicient diameter to prevent in principle gaseswhichcarrysaidsoimdwave.

ofthetwodestructive eflectson as has just been indicated, an tedbyrefiectionofsound V the sound wave beforeitreachestheoutletofthesiiencer sueh an embodiment is in in'whieh r withroushan'annularportla.

destroyed, and on the'other hand'of' Owing to the relative arrangement of the outl4, vertical none llisproduoed also sound It'willbeobservedthatwithsuchansrrsnsement, another destructive for the sound wave is involv'cd ifcareis taken to ar- I which are arranged in opposition but are connected together axially by the pipe I. An interference is produced inside said pipe I and, at the outlet of the pipe I, only an extremely small noise is perceived which is moreover drowned, as shown by the applicant's tests, by the mechanical noises of the engine.

It is moreover possible, in the case of a high speed engine operating with high compression, to multiply the number of apparatus and to make a series, or parallel, or series parallel connection. Industrial embodiments of a silencer will now be described which involve the principles and the phenomena previously indicated with reierence to Fig. 1. g In the embodiment which will be described hereinafter, in order to obtain the maximum speed of the vortical movement, the orifices of the various chambers have been so constructed as to form nozzles of the Venturi type.

Figs. 2, 3 and 3 illustrate an embodiment in which the chambers 4 and I are mounted on the exhaust tube Ii itself of the engine, two elements being connected in scrim. The two chambers 4 and I of each element are in communication with each other, through a flattened pipe I and are separated, at the outside of said pipe, by an inclined wall It.

The hot gases which arrive through the pipe I (arrow 1'') flow into the chamber 4 through the two ports I formed by the wills of the chamber 4 andtheendoftheinletl'ofthetubel. The gases then how in the direction of the arrows and the flattened pipe I, into the chamber I andthence. through the ports II, towards the channel I.

A second path. which is identical with the first. is eflected in the aecmd element, the gases finally issuing thrown the ips I".

It will be observed that the circulation of the gases in eaich element is effected in an identical manner with that described with reference to 1'1 1. Vm'tlcal aones'are respectively formed opposite the ports I and II and an interference produced in each flattened pipe I.

order to increase the speed of the vortices, walls of the chambers, adjacent the ends I- I of the pipe I,are inclined to form condivergent surfaces l4 and H which produce an expansion and a cooling.

=Ia'ch oblimiepartition I2 is arranged in such a manner that the increasing constriction of the tube is compensated by the lateral openings I.

In the chamber -4, the gases which arrive as shownabout the pipe I and through the ports I, tend to return to said chamber the cooled gases which flow through the pipe I towards the chamber I; this part of the apparatus operates as an elector.

In the chamber I', on the contrary, the gases whiph arrive through the pipe I tend to re-in- Ject the cooled gases into said chamber I and which escape through the ports II; this part of the apparatus operates as an injector.

In order to obtain the maximum friction be: tween the gaseous streams which enter and issue from each chamber, for the purpose of increasing the speed ofthe vortices. of the vertical zones, it

' is' preferable to place theoutlet of the venturi I4 slightly back from the inlet I, and the inlet dicated, as an ejector, and in the chamber I as an injector.

Figs. 4 and illustrate an embodiment of a silencer having eight chambers l, ,the oblique gases then flow from each chamber, through the pipes 5, intothe cone l2 whence they are exhausted through the tube 5*.

Opposite the ports 3 and Ill, vortical zones are produced, the vortices of which have a high speed.

In the embodiment of Figs. 4 and 5, each part.

operates as indicated with reference to the elements I, 4 and l of Fig. 1, the chambers not being placed in opposition.

Figs. 6 and 7 illustrate a modification of the embodiment shown in Figs. 4, 5. .In this example, two units are used arranged end to end. The left hand unit is identical with the device of Figs. 4 and 5. Under these conditions, the gases which issue from the first unit through the pipe E, flow into the cone I! placed in opposition to the cone II. The gases are then directed through radial pipes 5, into the chambers l, whence they flow, through the ports Ill, between the pipes 5 and finally into the atmosphere through the pipe 9, divergent walls being provided at I.

The second element (the right hand one) operates as indicated with reference to the parts i, i and 9 of Fig. 1. However, in this embodiment, an interference of the sound waves is caused in the space formed by the two cones lit-l2 and the pipe 3.

In the examples of Figs. 4 to 7, the cutting up of the sound wave is effected. The various radial parts behave like a single chamber.

It has been observed that, if a silencer according to the invention is mounted on a fixed engine,-or an automobile -engine,.a perfect silence is always obtained at the exhaust.

first are generally made of special alloys and constructed with thin walls, whereas the second are stronger and are made of cast iron for example.

In practice, in aeroplane engines. although an absolute silence is obtained at the exhaust with the device according to the invention, the walls of the exhaust manifold vibrate and go into turi being provided in each chamber at Is. The vortical movements take place in each chamber opposite the ports II. The various systems are mounted on a common manifold 9 formed by tubular parts 9 connecting the various systems together.

In this embodiment, not only is the benefit obtained of the destruction of the sound wave at the actual source where it is perceptible, but

the resonance of a thin walled manifold is stopped owing to the formation of the manifold by a plurality of elements acting to transfer the natural frequency of vibration of the manifold outside the audible frequencies.

The different embodiments previously described not only enable the sound wave to be completely destroyed, but also the power of the engine to be increased.

As the braking of the flow of the gases in the silencer is practically nil, the silencer according to the invention does not cause any loss of power. But, owing to the expansion of the gases and their cooling in the chambers, a regular contraction of said gases occurs and consequently a suction effect of the gases issuing from the engine.

when they issue from the silencer, the gases are at a'temperature of the order of degrees C.

and. the gain of power observed during tests attained 11.8 per cent.

It is obvious that the embodiments described and illustrated are only given herein by way of an indication and are non-limitative. Any modiflcations or variations which, in no way change 85 the main features hereinbefore explained. or the object aimed at, remain included in of the present invention.

What I claim as my invention and desire to secure by Letters Patent is: v 1. In a silencer for an internal combustion enthe scope gine or the like, a casing forming a gas expansion chamber having opposite end walls, an inresonance with the noise of the individual explosions of each cylinder.

In order to give a complete solution in each particular case, it is necessary to complete the silencer by a special construction of the manifold.

In order to facilitate the explanation of the complete solution proposed by the applicant, a simple straight engine II has been shown in Fig. 8. The cylinders II, 22, 23 and 2 are each provided, at the-exhaust, with a nozzle 5' which opens into a chamber I. The operation of each system 5'4 is comparable to that indicated with reference to the parts 5, I and l of 1, a venlet port located in one end wall and an outlet port located in the other end wall, said inlet and outlet ports determining a longitudinal axis in said silencer,- a concave bottom forming a downward extension below said axis in said casing. an upward extension above saidaxis forming a'concave top in said casing opposite said concave bottom, separation means separating one port and the concave top. on the one hand, from the other port and concave bottom, on the other hand, and means including a pipe extending transversely of said axis and connecting the interior of the casing within said concave top with the interior of said casing within said concave bottom through said separation means. there being means for connecting the inlet port with an exhaust pipe of said engine.

2. In a silencer for an internal combustion en-' one port and the concave top, on the one hand.

from the other port a d concave bottom, on the other hand, and means eluding a pipe extending transversely of said axis and connecting the tion which is inclined from the upper portion of I the inlet port down toward the lower portion of the outlet port. H

5. A silencer according to claim 1, in which a plurality of casings are connected inseries with the outlet port of one casing connected to the inlet port of the next adjacent casing.

6. A silencer according to claim 1, in which the casing is of greater dimensions vertically and longitudinally or horizontally than transversely, while the pipe connecting the interiors within the concave top and bottom of the casing extends substantially vertically and constitutes a flat pipe of greater dimension in the direction of the axis of the silencer than transversely of said axis.

7. A silencer according to claim 1, in which a plurality of casings are connected in series with the outlet port of onecasing connected to the inlet-port of the next adjacent casing, while having the inlet port in each casing larger than the outlet port of the next preceding casing, and wherein the concave bottom includes a chamber below the composite axis of the series and the separation means includes a bottom wall in the main portions of the case, and an upper wall in said lower chamber and a pipe in each case constitutes a nozzle connecting said lower chamber through said upper wall thereof and the lower wall of the main portion of the casing and also extending upwardly toward the interior of the concave top in each case.

3. A silencer according to claim 2, in which the casing has a plurality of additional extensions in the form of concave portions resembling the concave top and bottom and extending in a plurality of directions transverse of the axis so that a transverse section of all said extensions present a certaineformation, and the pipe is similarly provided with additional branches extending individually toward the interiors of said extensions or concave portions, while one portion of said pipe at one end of the casing is open so as to connect fully with the outlet port of the casing, the individual branches of the resulting star-shaped pipe structure forming the connections between said extensions, while other por tensions or concave portions, while one portion of said pipe at one end of the'casing is open so as to connect fully with the outlet port of one casing, the individual branches of the resulting star-shaped pipe structure forming the connec-= tions between said extensions, while other portions of said pipe structure intermediate said branches constitute the separation means in each casing, while the pipe in the second or successive casing opens fully to occupy the'inlet port of said second casing and connects with the outlet port of the first or preceding casing.

ROBERT PIERRE POMIES. 

